Medicament Delivery Device

ABSTRACT

An injection device with a feedback mechanism includes a housing for a medicament container having a stopper, a plunger rod for acting on the stopper, a button interactively connected to the plunger rod, an activation member having a flexible locking device releasably connected to the plunger rod, a drive force device, a locking member slideably between positions in which the locking member either completely or partially surrounds the flexible locking device, and a guide rod. Audible and tactile information that an injection has started is provided by the plunger rod&#39;s hitting the stopper.

This application is a continuation of U.S. patent application Ser. No.13/577,725 having a filing date of 2012 Aug. 14, which is incorporatedhere by reference.

TECHNICAL FIELD

The present invention relates to a medicament delivery device foradministering, disposing or delivering medicaments in a safe andreliable way. More particularly, it relates to an injection device formanually penetrating a needle arranged the said device and automaticinjecting a drug mixture from a multiple chamber container wherein anaudible and a tactile information is provided to the user indicatingthat the auto-injection has started.

BACKGROUND ART

There are a type of medicaments that can be stored for a long time andthat are filed in containers as e.g. cartridges, syringes, ampoules,canisters or the like, containing a ready-to-use medicament in liquidstate. However, there are also other types of medicaments that are amixture of two substances, a medicament agent (e.g. lyophilized,powdered or concentrated liquid) and a diluent (e.g. water, dextroxsolution or saline solution), wherein these type of medicaments cannotbe pre-mixed and stored for a long time because the medicament agent isunstable and can be degraded and loses its affect quickly. Hence, auser, e.g. a patient himself/herself, a physician, a nurse, hospitalpersonnel or trained persons, has/have to perform the mixing within alimited time period prior to the delivery of a dose of medicament to apatient. Further, some medicament agents are subject to meet significantchemical changes white mixing. Such sensitive medicament agents requirea particular treatment so that, when mixing said medicament agents witha diluent, unreasonable mixing force will degrade said medicamentagents.

In order to facilitate the mixing, a number of containers for mixinghave been developed comprising at least two chambers, known asmulti-chamber containers. These multi-chambered containers comprise afirst chamber containing the medicament agent and at least a secondchamber containing the diluent. These chambers are sealed off withstopper such/so that the medicament agents do not become degraded. Whenthe medicament agent is to be mixed shortly before administering,redirecting passages are opened between the chambers, usually bydepressing a distal stopper and in turn a divider stopper of thecontainer somewhat. The passages allow the mixing of the medicamentagent and the diluent and the medicament is ready for delivery.

The above mentioned requirements can be achieved by simple medicamentdelivery devices, such as a common hypodermic syringe, but the procedureis of course rather awkward, in particular for users not used to handledevices. In order to facilitate for the patient themselves to administerthe medicament with a predetermined dose in an easy, safe and reliableway and also to facilitate the administration of medicaments forhospital personnel in the same facilitated way, a number of automaticand semi-automatic devices have been developed in combination with thesemultiple-chamber solutions for obtaining a mixing before delivery.

A self-injection device arranged with a dual-chamber container, whereinboth the mixing and the injection are done automatically by mechanicalmeans, as springs and other means, is disclosed in U.S. Pat. No.4,755,189. A similar solution is disclosed in U.S. Pat. No. 6,793,646wherein the mixing of a dual-chamber cartridge is done automatically bysprings upon activation of the device and the injection is done bymanually applying a force to a plunger rod forwardly. A drawback withthese devices is that the mixing force, to which medicament agents aresubject to, is too high at the beginning due to Hookes law. Hence, themedicament agents can be degraded.

Another solution is disclosed in WO 2004004609, wherein both the mixingand the injection are done automatically by electronics controlledmeans. A drawback with this device is that the electronics are dependenton batteries and is very sensitive to noise, moisture, water, etc.;which can result in malfunctions. Even more the manufacture of thesedevices is more expensive than the manufacture of mechanical devices.

In U.S. Pat. No. 6,319,225 the mixing of a dual-chamber ampoule is donemanually. The device is set to be vertical on a flat plane and then adownward press on its proximal case causes a relative upward movement ofits plunger rod pressing a stopper of the ampoule with eye observationon actions inside the ampoule, such that a mixing is obtained. Though inU.S. Pat. No. 6,319,225 is disclosed that the best suitable process formixing a medicament agent with a diluent, is by performing manualcontrol of the diluent flow with adequate slowness which will bemonitored by eye observation; a drawback with this device is that themixing force, to which medicament agents are subject to, can be high ifthe user is stressed and wants to use the device as soon as possible.Hence, the medicament agents can be degraded.

Moreover, the handling and safety aspects of injector devices, having acertain degree of automatic functions, as well as immediateaccessibility in emergency situations are issues that attract a lot ofattention when developing this type of devices.

One important safety aspect when handling an auto-injector which is usedto achieve a manual mixing and an automatic injection, is the locking ofthe injection means, e.g. a compressed spring actuating on a plungerrod, before the manual mixing have been completed.

One such a device is disclosed in U.S. Pat. No. 6,893,420 wherein aself-injection device is arranged with a dual-chamber body. The mixingis done manually by a screw-tightening operation and the devicecomprises locking means for locking a latch means that prevent theautomatic penetrates and injection means from being released before themixing has been completely finished. However, this solution is ratherbulky and relies also on many components acting in co-operation and insequence, one triggering another, which may lead to a mal-function,mal-dose accuracy, or that the device becomes complicated, hence notuser friendly. This device suffers from the drawback that locking meanshas to be actively removed from the device after the mixing has beenfinished. This is a step which is not intuitive for a user, who will tryto push the locking means instead of removing them. Another drawback isthe dose accuracy, since the penetration starts pushing the stoppers,the medicament will start to be expelled during the whole penetrationsequence, leading to so called wet injections and delivering ofmedicament through the whole penetration tissue instead of injecting therequired dose at the intended penetration depth.

Another such a device is disclosed in WO2007/115424A1 which relates toan injection device having a container holder having a multi-chambercontainer within, which is manually movable relative to the injectiondevice for the purpose of mixing the components within the multi-chambercontainer. The device further comprises a spring which can bear on apart of the injection device, and a coupling element for coupling thecontainer holder to the spring such that, during the movement of thecontainer holder into the injection device, the spring is tensioned. Thedevice also comprises an activation knob and a push button, wherein theactivation knob has to be rotated for forcing the push button toprotrude from the housing and thereby setting the device in a ready forinjection delivery state. However, this solution suffers from thedrawback that the activation knob has to be actively manipulated forreleasing the push button after the mixing has been finished. This is astep which is not intuitive for a user, who will try to find where thepush button or activation means are located instead of rotating theknob.

Moreover, another device disclosed in WO2009/147026A1, which is anearlier patent application of the present applicant suffer from theproblem of indicating the user when the auto-injection has started andalso when the auto-injection is finished.

Even though the devices according to U.S. Pat. No. 6,893,420,WO2007/115424A and WO2009/147026A1 have proved to function well anddisplays a degree of safety, there is always a desire for improvement ofsuch devices, among them being the design of the mechanism in order tosimplify the manufacture and assembly in order to reduce costs but atthe same time having improved features maintaining or even improving thereliability of the safety and function of the device.

SUMMARY

The various objects and advantages of this invention can be obtainedfrom an injection device having a feedback mechanism, the device beingfor penetrating a needle arranged to the device into an injection siteand automatically injecting a medicament. The device includes:

a housing configured to hold a medicament container having a stopper;

a plunger rod having a proximal end and being configured to act on thestopper;

a button interactively connected to the plunger rod;

an activation member having a tubular flexible locking device releasablyconnected to the plunger rod;

a drive force device pre-tensionedly arranged between a distal portionof the activation member and the proximal end of the plunger rod;

a locking member coaxially and slideably arranged around the activationmember between a first position, in which the locking member completelysurrounds the tubular flexible locking device, and a second position, inwhich the locking member partially surrounds the tubular flexiblelocking device; and

a guide rod coaxially arranged between the distal portion of theactivation member and the stopper, the guide rod having a proximalportion that extends beyond the proximal end of the plunger rod.Displacement of the button causes disconnection of the tubular flexiblelocking device and the plunger rod such that the drive force devicecauses the proximal end of the plunger rod to hit the stopper, therebyproviding audible and tactile information that automatic injection hasstarted.

BRIEF DESCRIPTION OF FIGURES IN THE DRAWINGS

In the following detailed description of the invention, reference willbe made to the accompanying drawings, of which

FIG. 1 is an exploded view of the auto-injector according to theinvention,

FIG. 2 is a cross-sectional side view of the auto-injector according tothe invention in a pre-mixed position,

FIG. 3 is a cross-sectional side view of the auto-injector according tothe invention in a medicament mixed position,

FIG. 4 is a cross-sectional side view of the auto-injector according tothe invention after the push button has been depressed,

FIG. 5 is a cross-sectional side view of the auto-injector according tothe invention when the auto-injection is almost finished,

FIG. 6 is a cross-sectional side view of the auto-injector according tothe invention when the auto-injection is finished.

DETAILED DESCRIPTION

In the present application, when the term “distal part/end” is used,this refers to the part/end of the delivery device, or the parts/ends ofthe members thereof, which is/are located the furthest away from themedicament delivery site of the patient. Correspondingly, when the term“proximal part/end” is used, this refers to the part/end of the deliverydevice, or the parts/ends of the members thereof, which, is/are locatedclosest to the medicament delivery site of the patient.

The present invention relates to an injection delivery device comprisinga housing formed by a distal housing part 10 and a proximal housing part12, and wherein the distal housing part comprises a first distal housingpart 10 a and a second distal housing part 10 b. It is however to beunderstood that other designs are feasible within the present invention.Further, the outer surface of the proximal housing part is arranged withat least one flexible tongue having an annular protrusion (not shown)which is intended to fit into a corresponding annular recess on thesurface of the second distal housing part as will be described below.

The device further comprises a proximal housing part 12 into which amulti-chamber container 20 is arranged and wherein said proximal housingpart is arranged to be manually displaced into said distal housing formixing at least two substances arranged inside said container; a plungerrod 40 arranged to act on a distal stopper 21 which is arranged insidesaid container; a push button 70 protruding from said distal housingpart and being interactively connected to the plunger rod; an activationmember 30 comprising tubular flexible locking means 34 releasablyconnected to said plunger rod; drive force means 100 pre-tensionedarranged between a distal end surface 31 of the activation member and aproximal end wall 41 of the plunger rod; a locking member 50 coaxiallyarranged around said activation member and being distally slideable inrelation to said activation member by said proximal housing between afirst position wherein said locking member completely surrounds saidtabular flexible locking means holding said plunger rod and thereby saiddrive force means in a pre-tensioned state and a second position whereinsaid locking member partially surrounds said flexible locking means; anda guide rod 60 coaxially arranged within the drive force means 100between the distal end surface 31 of the activation member and thedistal stopper 21, and wherein a proximal portion of said guide rodprotrudes through the proximal end wall of the plunger rod determining afirst predetermined distance “A” between the proximal end wall and thedistal stopper, as seen in FIG. 3, such that when said push button isproximally displaced, it forces the plunger rod, the activation memberand thereby the guide rod to be proximally displaced, whereby thetubular flexible locking means comes completely out of contact with thelocking member and with the plunger rod, primary allowing the plungerrod to be proximally displaced the first predetermined distance by theforce of the pre-tensioned drive force means such that the proximal endwall 41 of the plunger rod hits the distal stopper 21 for providing anaudible and tactile information that the aromatic injection has started.

The proximal housing part 12 houses the multi-chamber container 20,wherein a proximal neck portion 23 of the multi-chamber container fitsinto a threaded neck portion 13 of the proximal housing part and whereinsaid multi-chamber container comprises at least two medicamentsubstances arranged in each chamber, a distal stopper 21, a proximalstopper 22, and redirecting passages between the chambers. Further, theinner surface of the second distal housing part is arranged with threadsarranged to interact with corresponding threads arranged on the outersurface of the proximal housing part.

The device further comprises a plunger rod 40 arranged to act on thedistal stopper 21 which is arranged inside said container. The plungerrod is formed as a tubular member with an outer diameter somewhatsmaller than the inner diameter of the container body to be used.

The push button comprises a distal transversal wall 74 having en innersurface located at a second predetermined distance “B” from the distalend surface 31 of the activation member, as seen in FIG. 3; at least twofirst proximally extending tongues 71, wherein each tongue has aproximal surface abutting a distal annular surface of the plunger rod;and at least two second proximally extending tongues 72, wherein eachtongue comprises at least one longitudinally extending slot 73.

Surrounding the plunger rod is the activation member 30 with a mainlytubular shape. The proximal end of the activation member comprisestubular flexible locking means 34 so as to form flexible tongues. Eachtongue has an inclined transition surface 90 which meets with aband-shaped part 38 with enlarged diameter forming the proximal annularsurface of the tubular flexible lading means. On the inner surfaceadjacent the transition surface a generally radial inwards directedledge 33 is arranged, with a shape as to fit into a groove 46 of theplunger rod. The activation member is further provided with flexiblehook means 32 so as to form at least one flexible tongue having a radialoutwardly directed hook 37 at its outer end, and having a protrusion 35with an inclined surface. The flexible hook means 32 are arranged tointeract with annular holding means 11 formed as a u-shaped ledgearranged on the inner circumference surface of the first distal housingpart. The activation member is also provided with at least one radiallyoutwards directed protrusion 33 interacting with at least onelongitudinally extending slot 73 of the push button, such that theactivation member is longitudinally movable in relation to said pushbutton. Further, the activation member also comprises at least twooppositely arranged stop ledges 39 directed radially outwards from theouter surface on either side.

The locking member 50 also of a generally tubular form comprises at itsdistal end at least two oppositely arranged cut-outs of a generallyrectangular shape forming at least two distally extending tongues 51,and wherein the widths of said cut-outs correspond to the width of thestop ledges 39 of the activation member. The locking member alsocomprises a proximal end having a distal annular ledge 52 and a proximalannular ledge 53 on its outer surface.

The device further comprises a compression spring 80 arranged betweenthe at least two oppositely arranged stop ledges 39 of the activationmember and the distal annular ledge 52 of the locking member.

The function of the injector according to the invention will now bedescribed in connection with the FIGS. 2-6.

The injector will be delivered to the user as shown in FIG. 2, where themulti-chamber container is placed in the proximal housing part and thedistal housing part is attached to the proximal housing part. Thetubular flexible locking means 34 are engaged to the plunger rod throughthe generally radial inwards directed ledges 33 fitting into the groove46 of the plunger rod. The locking member being coaxially arrangedaround said activation member in the first position therein said lockingmember completely surrounds said tubular flexible locking means holdingsaid plunger rod and thereby said drive force means in the pre-tensionedstate.

When a mixing is to be performed, the proximal housing part is screwedinto the distal housing part until the plunger rod and the guide rodswhich are static in relation to the proximal housing part, has shiftedthe distal stopper proximally with respect to the container such thatmedicament substances inside said multi-chamber container have beencompletely mixed, see FIG. 3. In this mixed position, the annularprotrusion of the at least one flexible tongue on the outer surface ofthe proximal housing part 12 fits into the corresponding annular recesson the inner surface of the second distal housing part.

At the same time the annular distal end part of the proximal housingpart abuts the proximal annular ledge 53 of the locking member andforces said locking member axially towards the distal end of the deviceagainst a force of the compression spring. The compression spring isthen tensioned. A portion of the band-shaped part 38 is then partiallysituated outside the proximal annular end of the locking member, as seenin FIG. 4. The at least two distally extending tongues 51 of theactivation member will then come in contact with the inclined surface ofthe protrusion 35 of the hook means 32 on the activation member wherebythe hooks 37 are moved radially inwards.

The next step is to connect a needle or a safety pen needle to theproximal end of the proximal housing part, and to achieve a manualpenetration of the needle into an injection site as e.g. the tissue of apatient.

When activating the injection device, the user merely depresses the pushbutton, FIG. 4, wherein at the at least two first proximally extendingtongues 71 of the push button which are abutting the distal annularsurface of the plunger rod, forces the plunger rod to be moved towardsthe proximal end of the device. Since the plunger rod is connected tothe activation member by the generally radial inwards directed ledges 33fitting into the groove 46 of the plunger rod, the activation member isalso forced towards the proximal end of the device, and since the distalend of the guide rod is abutting the distal end surface 31 of theactivation member, the guide rod is also force towards the proximal endof the device starting to force the distal stopper 21 towards theproximal end of the device. During the proximal displacement of theactivation member, the hooks 37 pass inside the annular holding means 11which is formed as a u-shaped ledge arranged on the inner circumferencesurface of the first distal housing part, and the band shaped part 38comes completely outside the proximal annular end of the locking member.The resilient properties of the tubular flexible locking means 34 of theactivation member forces the band shaped part 38 to flex radiallyoutwards causing the ledges 33 to come out of the groove 46 of theplunger rod, which then is free to move due to force of thepre-tensioned drive force means inside the plunger rod. Also when theband shaped part 38 flexes radially outwards, the inclined transitionsurfaces 90 of the tubular flexible locking means 34 then abut againstthe proximal annular end of the locking member. The force of the driveforce means urges primary the plunger rod to be proximally displaced thefirst predetermined distance between the proximal end wall of theplunger rod and the distal stopper, such that the proximal end wall ofthe plunger rod hits the distal stopper producing an audible and tactileindication. The distal stopper forces the proximal stopper proximallyand the mixed liquid substance of medicament is injected into thepatient tissue until the proximal stopper reaches the inner proximal endof the container, as seen in FIG. 5.

Just before the proximal stopper reaches the inner proximal end of thecontainer, the distal annular surface of the plunger rod passes theproximal annular surface of the tubular flexible locking means 34 cominginto the inner circumferential surface of the band shaped part 38whereby the inclined transition surfaces 90 of the tubular flexiblelocking means 34 slide over the proximal annular end of the lockingmember due to a remaining force on the drive force means and the forceof the tensioned compression spring 90 forcing the activation member tomove distally the second predetermined distance. When the activationmember is distally displaced, the at least one radial outwards directedprotrusion 36 slides within the at least one longitudinally extendingslot 73 of the push button, the stop ledges 39 hits the distal surfaceof the annular holding means 11 which is formed as a u-shaped ledgearranged on the inner circumference surface of the first distal housingpart, and the distal end surface 31 of the activation member hits theinner surface of the transversal wall 74 of the push button producing anaudible and tactile indication that the injection is finished.

It is to be understood that the tubular flexible locking means arearranged to be released from said plunger rod only after said lockingmember is moved from the first position to the second position and saidpush button is proximally displaced. If the mixing is not completelyperformed i.e. the proximal housing part has not been completelydisplaced into the distal housing part such that the annular distal endpart of the proximal housing part which abuts on the proximal annularledge 53 of the locking member has not forced said locking memberaxially towards the distal end of the device against the force of thecompression spring 80 and thereby the flexible hook means 32 has notbeen flexed radially inwards. Therefore, if the user attempts to depressthe push button before the mixing is completely done, the outwardlydirected hooks 37 of the flexible hook means 32 will engage the annularholding means 11 which is termed as a u-shaped ledge arranged on theinner circumference surface of the first distal housing part foravoiding premature activation of the device.

It is to be understood that the embodiment described above and shown inthe drawings is to be regarded as a non-limiting example of theinvention and that it is defined be the patent claims.

What is claimed is:
 1. An injection device having a feedback mechanism,the injection device being for penetrating a needle arranged to thedevice into an injection site and automatically injecting a medicamentand comprising: a housing configured to hold a medicament containerhaving a stopper; a plunger rod having a proximal end and beingconfigured to act on the stopper; a button interactively connected tothe plunger rod; an activation member having a tubular flexible lockingdevice releasably connected to the plunger rod; a drive force devicepre-tensionedly arranged between a distal portion of the activationmember and the proximal end of the plunger rod; a locking membercoaxially and slideably arranged around the activation member between afirst position, in which the locking member completely surrounds thetubular flexible locking device, and a second position, in which thelocking member partially surrounds the tubular flexible locking device;and a guide rod coaxially arranged between the distal portion of theactivation member and the stopper, the guide rod having a proximalportion that extends beyond the proximal end of the plunger rod; whereindisplacement of the button causes disconnection of the tubular flexiblelocking device and the plunger rod such that the drive force devicecauses the proximal end of the plunger rod to hit the stopper, therebyproviding audible and tactile information that automatic injection hasstarted.
 2. The device of claim 1, wherein the tubular flexible lockingdevice disconnects from the plunger rod only after the locking membermoves from the first position to the second position and the button isdisplaced.
 3. The device of claim 1, wherein the plunger rod includes acircumferential groove and the tubular flexible locking device includestongues having respective inwardly directed ledges configured to fitinto the circumferential groove.
 4. The device of claim 1, wherein theactivation member comprises opposite radially outwardly directed stopledges, and the locking member comprises distally extending tonguesseparated by gaps having widths that correspond to widths of the stopledges.
 5. The injection of claim 4, wherein the locking device furthercomprises an annular ledge, and the injection device further comprises aspring disposed between the stop ledges and the annular ledge.